Machine for finishing irregularly shaped articles



2,426,764 MACHINE FOR FINISHING'IRREGULARLY SHAPED ARTICLES Sept. 2, 1947. s. A. CZARNECKI s Sheets-Sheet 1 Filed Oct. 26, 1945 INVENTOR Sigma/4 d/I. (zam ecki M f M22141 ATTO R NEY.

5. A. CZARNECK! Sept. 2, I947. MACHINE FOR FINISHING IRREGULARLY SHAPED ARTICLES 3 Sheets-Sheet 2 Filed Oct. 26, 1945 INVENTOR' S/gmufld 44- Czarnecki ATTORNEY.

P 1947- I s. A. CZARNECKI 2,426,764

MACHINE FOR FINISHING IRREGULARLY SHAPED ARTICLES Filed Oct. 26, 1945 s Sheets-Sheet s INVENTOR i /58 [04 I SIgHfl/Hd/l. Czarnecki F M Km ATTORNEY.

Patented Sept. 2, 1947 FOR FINISHING IRREGULARLY SHAPED ARTICLES MACHINE Sigmund A. Czarnecki, Glastonbury, Conn., as-

signor to United Aircraft Corporation, East Hartford, 001111., a corporation of Delaware Application October 26, 1943, Serial No. 507,713

22- Claims.

This invention relates to machines forgrinding and polishing irregularly shaped articles.

While the features of the present invention may be employed to advantage in the manufacture of numerous articles, they are of particular importance in connection with the grindingand polishing of propeller bladesjand for purposes of illustrating a practical embodiment of the invention, the improved features of the invention are described herein inconnection with the manufacture of airplane propeller blades.

Propeller blades of this type not only change in pitch from the hub end to the tip end of the blade, but the camber side of the blade also has a' constantly changing contour from end to end.

It has previously been necessary to grind and polish such'blades to finished shape'by hand, work requiring great patience and ski1l and of every time consumingnature. r p i An object of this invention isto' provide a machine for grinding and polishing irregularly shaped articles, and moreparticularly to provide a machine capable of grinding and polishing both the flat and camber sides of airplane propeller blades quickly andiaccurately to finished dimensions.

Another obiect'of this invention is to provide a blade finishing machine having a grinding or a polishing belt beneath which the blade is longitudinally reciproca-ted for enabling both thefiat side and the camber side of the blade to be finished to identical pitch upon movement of the blade about its longitudinal. axis. to bring the selected side of the blade uppermost. p

A further object of the invention istoj provide a blade finishing machine of the abovetype having an accurately formed, .or contoured, backing roll for the abrasive belt at its'pointof contact with the blade which is rotated ina predetermined relationship relative to the longitudinal movement of the blade for accurately determining the finished shape of the camber side of the blade.

A still further object of the invention is the provision of'improved cushioning means between the formed surface on the roll and the abrasive belt for preventing crushing of the abrasive particles on the belt. j I I .i

These and other objects ofthe' invention Will be apparent from the following detailed 'descri gi-v tion of a preferred embodiment thereof, shown for purposes of illustration only. and not intended to limit the scope of the invention, reference being had for this purpose to the claims presented herewith.

In th drawings, wherein similar reference characters refer to similar parts throughout the several views, V i

Fig. 1 is aside elevation partly in section of a machine embodying the improvements, certain parts being broken'away to facilitate illustration;

Fig.2 is an end View of the machine as viewed from the right hand end of Fig. 1;

' Fig. 3 is a detail sectional view taken in front of the contact roll showing the tip end of the blade beneath the roll;

-,Fig. 4 is a similar view showing the hub end of the blade beneath the contact roll;

Fig. 5 is an enlarged detail view showing the cam and rail mechanism for adjusting the blade relative to the contact roll in accordance with pitch changes in the blade;

Fig. 6 is an enlarged sectional detail on line 66 of Fig. '7 showing the contact roll in engagement with the hub end of the blade;

Fig. 7 is an end view of Fig. 6, with parts broken away; 7 I

Fig-8 is a view similar to Fig. 6 but showing the contact roll in position for grinding the face, or flat, side of the blade;

Fig..' 9 is a sectional detail'of the contact roll and blade, and

Fig. 10 is a sectional detail of the clutch for releasing the contact roll. I

'Referring more particularly to the drawings, it will bev observed that the frame of the machine includes main front and back columns I0 and 12 connected rigidly in spaced relation by a transverse frame member I4, and a secondary back column 18 connected at its upper end to column l21by a horizontal stay rod 22. These columns are further connected adjacent their lower ends by the horizontal bed of the machine including frontand' back ways which rest on brackets 24 formed integral with the columns adjacent their lower ends. These ways comprise outwardly facing channel members 26 and 28 secured respectively to the front and back columns by bolts (not shown),fand lower and upper horizontally disposed flat rails 30 and 32 which project inwardly toform; with'the backs of the channel members,

inwardly facing right angular channel ways in which rollers34 of a longitudinally movaJble carriage 3B are received, certain of these rollers engaging the'uppe'r rail 30 while others engage the lower rail 32. in a well known manner. The carriage'SG is reciprocated longitudinally of the bed by means of a usual hydraulic mechanism including the cylinder 31 having fluid connections 377a and 371) at opposite ends thereof and having a piston (not shown) for reciprocating a connecting rod 310 which is connected at its free end'to the bracket 31d fixed to the carriage. The horizontal extensions of the ways beyond the main and secondary columns are supported on brackets 24 formed as integral parts of pairs of connected pedestals 38, suitably located at spaced pointstherealong. V V

Column! 8'has'a'transverse shaft 39 journaled therein .atrits upper end carrying a cylindrical rollerldfl for 'supporting one end of a generally 2,426,764 1 T i; Tr 3 4 r horizontalendless beltjlz having an outer abrading or eel sli i fe r e ee ee psi eilend belt 52 travels over a similar roller 43 which is journaled between parallel arms 44 of a bracket 46 carried by the frame member 14. Frame merl- T u,

ber I4 also supports a franie'EB phoneme H which carries a roller 52 smaller than the-end rollers 60 and 43 and biased upwardly intq engagement with the under side'o'f' theQbTeltQZEb-ya compression spring 54. It will be observed that the lower reach of the abrasive belt passes between the front and rear columns of the'frame and beneath the transverse member I4 in a generally horizontal position over the carriage, this passing at its lowest point ontapt roll 56 on a shaft 58.. io rnall dl s1 cemh wa iv; m d arcuate arms fi Bfan'dfGZ 'ot a" glenerally U-shaped vertically"adjustable roll-carrying bracket '64.

Bra k tfie i vert a l a I a ram spaced vertical c1isp'ose d guides, one of: which uidesfifihave fiat- 4 nd fi i h h V erbos'ses -"It! and m er 14. The Tread gen'erallyhellcrank .qn ffi' iou in ll' d h ft Bjand l2 and-includes l r "d s t llr i it h e iai 11' and '18 havingrollrs'tfi and 82' pivotally 'supported in their ends This bracket alsdirrclu'des vert'" lTeXtehLddjalrrhs dfl'8'a cori1rected by a verticatweb 19 carrying thejbosse's "'lflahd revi us y s etened dli i e n i" the froht face of'i'ts u'p'p'erhd' alongitu V allyades n me ber 84 cerried ri i fim 8M on 'frarnemmber t4; iirnit the clockwise movement oi bracket member about itspiv'ot s' 't w q he} b a mem .Whic rmi pivoted. x 'lfid'bn the main two widely spa c lit r t engeget e r GL-PjfJftlXlllfldtQl "the; shape'jcf'the finished blade. The cradle is 'su pprted on; the carriage at longir tudinally paedf p'o'iritsiby f ieper'i-dihgf 'a'rcuajte ro'kers llfijwhich restf'on rollers H2 disposed iria'rcs struck ab uthalo 7 udihal axis 14 of a 'propellerblan ron the cradle.

' Thebradl 'SZB provided at spaced points aldngits length h pp'ositely laterally extended e nsnt which-s ortrails mend no, adapted to be constantlfirleng 4 ed by the rollers 80 'andtlZ on thear ls T 'and 1' of the hea'd bracket fjl'hese shown rnos tf lea'rlyinf fig. 5', va'ry diif e'r-v muslin-height frombn -end teflt oth r or the cradle, the front rail H8 being" highest at the huh" er-rd or thq-i radle aha iewst at the'tip end thereof; while the b ackfail I 20 f is eorrespon'ding'ly low at the hub end and" high at the tip end. The difference in-elevation of th top flof theiails at any station along the length of the propeller is such that a straight line con nectlng the tops of the rails will represent the angle of pitch of the blade at this station measredrroinehonmmer line. It will thus be evi-' hem that as the rollers 80 and 82 travel along the tops of rails H8 and I20 during the longi- -tudinal reciproationof the carriage, the cradle will be rocked-onrollers H2 so as to maintain the transverse axis of the blade constantly par all'el with the cylindrical face of the roll 56. Thus,

if the flat face of the propeller is being ground, this 'face'will, at all times, be parallel with the longitudinal face of the" roll 56.

The contact roll 56 as shown in detail in Figs. 6 to 10, comprises a-h'ollow; relatively thickj'cylin dr'ical externally grobved portion I22 fsuitablysecured tdannular end plate members-l M enl 2 6, which are fixed as'by keys 128' to'the fs h'a ftfBB forretation therewith in the arm st'fl and 62. fiThe cylindricalportion 22' of roll'f'fifi has aportion l 30 of tsper'iphe y-ungmwed' representing ase 'ginnt of approximately ffio degrees, although the extent" of this uncut surfacewill vary withhrums provided for propellerbla'desof different length. The remaindenof the periphery of theTtpOhtact roll has a'c'entral groove I32 cut th'e'r'eiinhf conthe blade-along-the'length thereof. Thus; at the poiht l3- the" contp'urpf groove l'az -eerrespehds to the contour "of the camber side "of the plan at the station adjacent the hubfof thebladeWhile at the point I 35, theeontour of groove f3 2f corresponds to the 'cofritourflofthecamber. side atthe tip stationef'thejblaue Hereitwill be note'd that from -pointslfl34"an 1136 the gmsve- 5 exte dedtafrgentially and" merges 'into the uneat portion bfthe' periphery of "the "route. ItTwill thus be evident that the groove formed in'the sfui'face offthe roll 5 tv "is a surface irhpres'sionof' theeamber me offthe blade-wrapped aroundlthe roll and developed to eliminate pitch changes-in theblade. I, p p

Cooperating means are provided oh I the'tn'ovable carriage" of the" machine and"o'ri the froll "56 for rotatihgtherollin synch V ism vi'rithlthelongitudinal movement flofthe blade "therebene'aithfso that the portion? of The blade is" beneath the] rolli'alw'ays' bhrrespondsfwith the; "grhove .in the roll. To=this'e'nd,fa gear wheel 38d nalledfforrotation'onshaft 58 adjacent Plate fl'26' 0f "the rO11finDb'S'itio1l"t0mesh Witha longitudinalrackl@Oje'arriedfbyspacedvertically adjustable upri hts 1'42 and fits "ohthe 'c 'arr iage. The gear 11661 138 lifelGasfiblYblihfietd with roll 56 by meah r 'a clutch including a plurality of pins 'l harried by gear" wheel "I 3 8' "which are fo'reea into suitable apertures"i'rifthe race of the 7 plate 1: I26 "against the action" fofi compression springs I50 by the projecting endSWBZofthepins |48 as; the spann r: my 154 mated eh the threaded PO'I'f-ionflififbf ISHaft 58. IFWillthllS be "Tobvious that wi htheiai ameter "of "gear w-heel lea-equal to thatfo'f' theronfss' the Iatter'will'have a peripheral speed equivalent to the linear speed of"re'ciproca'tion of'th blank [08 on thehamege';

Means are also provided forcuslfioninglthe abrasive belt" 42 Where it passes beneath the con tact roll5ii. This means comprises a freely; rotat ing rubber belt I 58 supported on four small rollers {59; rsmf'rsl 'a zijl'szi'if'rhef loner {-59 ifs-sournaied' betweerifthe ffspaded arms} "60 and-i622, of bracket fin whil e the rollers I60 [6] ahdlBZ are journaled in extensions I64, I 66, and I68, of these spaced arms. It will be noted that the rollers I6I and I62 are disposed substantially in the normal path of the lower reach of the belt 42 so that a line connecting the bottoms of these rollers will pass substantially through the bottom of the groove I32 in roll 56 at its deepest point I34.

The abrasive belt 42 is driven by a motor (not shown) by means of a belt I driving a fixed pulley I12 on the shaft I14 to which the roller 42 is suitably fixed, the travel of the belt being clockwise as viewed in Fig. 1 and as indicated by the arrow in that figure.

The operation of the machine to grind or polish the camber side of the blade will be first described. A blank I08 to be ground is placed camber side up on the work supporting carriage 98 with its hub end secured in the clamp I06. It will be understood that the carriage 36 is normally stopped in its extreme right hand position, as viewed in Fig. 1, in which the tip of the blade supported on the carriage is disposed somewhat to the right of the contact point of the work beneath roll 56, this point of course constituting the lowest point of the abrasive belt 42.

The blade is properly positioned relative to its longitudinal axis, by the series of supports I04, which together form a fixture for supporting the blade at a plurality of points, or stations, along the latter in the proper angular relation to the top of the rails H3 and I20. It will be evident that as hydraulic fluid is admitted through connection 3112 (Fig. 1) to the cylinder 3! of the hydraulic mechanism, the piston and connecting rod 310 of the latter will move the carriage to the left, as viewed in Fig. 1. The tip of the blade is thus brought beneath the rapidly moving abrasive belt 42 at the contact point of the blade beneath the roll 56. Roll 56 has been rotated by the rack I40 and gear I38 into a position in which the point I36 (Fig. 6) at which the groove I32 corresponds to the tip contour of the blade on the roller 56, is at the bottom or contact point. It will be understood that during the slow rotation of the roll 56 the belt 42 passes therebeneath at a high rate of linear speed.

As the carriage continues to move slowly to the left, the roll 56 slowly moves in a clockwise direction (Fig. 1), the linear speed of the periphery of the roll being equal to the linear speed of movement of the carriage, so that the contour of the ground blade face at each station along the blade exactly corresponds to the contour of the groove at the corresponding station of the periphery of the roll. During this movement of the carriage the rolls 80 and 82 are travelling along the tops of rails H8 and I on the carriage. As previously pointed out a straight line connecting the tops of these rails at any station along the blade will coincide with the pitch at that station. Accordingly, as the carriage and the rails move longitudinally relative to the rolls 80 and 82, the cradle 98 will be rocked about a center II 4 which coincides with the longitudinal axis of the blade so that the blade face is continuously maintained at the proper angle relative to the face of the roll 56, while the head bracket member 14 will rock about the axis of trunnions I5 as determined by the height of the top surfaces of the rails I I8 and I20. This movement continues until the hub of the blade has reached the contact point I34 on the roll 56 as shownin Figs. 4, 6 and 7. Fluid is now admitted through connection 31a to return the carriage,

during which return movement the roll is slowly rotated in a counter clockwise direction.

The fiat, or back, side of the blade can be ground by clamping the blank I08 with the flat side thereof uppermost. In this instance, the gear I38 is freed from its driving connection with contact roll 56 so that the latter is driven freely at high speed by the abrasive belt 42. This is accomplished by backing off the spanner nut I54 which allows the pins I48 under the action of compression springs I50 to be withdrawn from the apertures in the plate I26. Due to the high speed of rotation of roll 56 the fiat side. of the blade is ground by the uncut portion I30 of the 7 contact roll 56, as if the roll were a continuous uncut roll.

As a result of the improvements above described, it will be evident that a blade grinding and polishing machine is provided which is capable of finishing both the flat and the camber sides of an airplane propeller blade while accurately maintaining the pitch identical on both sides of the blade. It will also be evident that the grinding and polishing of propeller blades can, as a result of these improvements, be carried out more quickly and eificiently than heretofore the losses in man power andspoiled blades being tremendously reduced. It will also be evident that due to the provision of the rubber backing belt I58, which cushions the abrasive belt 42 and prevents crushing of the grit or cutting particles thereon the life of the belt 42 is greatly increased, as well as its speed of cutting.

While the invention has been described with particular reference to a preferred embodiment thereof, it is to be understood that many changes may be made in the construction of the machine without departing from the invention as defined by the following claims.

What I claim as new and desire to secure by United States Letters Patent is as follows:

1. In a machine for finishing irregularly shaped articles, in combination, a belt having an external abrasive surface, a work support, a contact roll for positioning said belt relative to a piece of work on said support, said roll having a peripheral depression therein of varying shape around the periphery of said roll and constitut ing an impression of a surface of the finished work piece, means for effecting relative movement of saidroll and said work piece longitudinally of the latter, and means for rotating said roll about its axis in timed relation with said longitudinal movement.

2. In a machine for finishing irregularly shaped articles, in combination, a travellin belt having an abrasive surface, a work support, a contact roll for positioning the abrasive surface of said belt relative to a piece of work on said support, said roll having a peripheral depression therein constituting a developed impression of a surface of a finished work piece. means for effecting relative reciprocatory movements between said roll and said work piece, and means for oscillating said roll about its axis in timed relation with said reciprocatory movements.

3. In a machine for finishing irregularly shaped articles, in combination, a travelling belt having an abrasive surface, a Work support, a contact roll for positioning the abrasive surface of said belt relative to a piece of work on said support, said roll having a surface depression therein about a portion of its periphery constituting a developed impression of a surface of a finished work piece, means for effecting relative recipro 11. In. a machine for finishing propeller blades having pitch changes between the hub and tip a blade supporting carriagev disposed on one side of a generally horizontal reach of said belt, a pressure roll carried by said head on the other side of said belt for engaging the latter with a blade on said carriage, said roll having a, peripheral groove therein constituting a developed surface impression of the camber side of the finished blade, means for reciprocating said carriage lon- 'gitudinally relative to said roll, cooperating means on said head and carriage for rocking the latter about the longitudinal axis of the blade supported thereon in response to said reciprocating movemerits, cooperating roll driving means carried by said carriage and roll for rotating the latter about its axis in timed relation to the longitudinal movements of said carriage including a gear coaxial with said roll and normally rotatable therewith, and means for disconnecting said gear from said roll whereby to permit said roll to rotate freely.

'12. In a machine for finishing'propeller blades having "pitch changes between the hub and tip portions thereof, in combination, a head, a'plurality of guide rollers supported in generally parallel relation about said head, a belt running over said rollers having an outer abrasive surface, a blade supporting carriage disposed on one side of a generally horizontal reach of said belt, a pressure roll carried by said head on the other side of said belt for engagin the latter with a blade on'said carriage, said roll having a peripheral groove therein constituting a developed surface impression of the camber side of the finished blade, means for reciprocating said carriage longitudinally relative to said roll, cooperating means on said head and carriage for rocking the latter about the longitudinal axis of the blade supported thereon in response to said reciprocating movements, cooperating means carried by said carriage and roll for reversely rotating the latter about its axis by the longitudinal reciprocating movements of said carriage, means for effecting adjustment of said roll and carriage toward and from each other, and means, for maintaining a substantially constant tension on said belt during said adjustments."

13. In a machine. for finishing propeller blades, in combination, a frame having a generally horizontal bed, a, blade support 'movable longitudinally on said bed, a head bracket carried by said frame above said bed, a pressure roll adjustably supported on said bracket, guide rollers carried by said frame on opposite sides of and remote fromsaid roll, an abrasive belt running over said rollers having a reach passing between said roll and the blade on said support, a plurality of rollers more closely spaced about said roll in generally parallel relation thereto, and a, cushioning belt running over said second mentioned rollers and supported thereby independently of the supporting rollers for said abrasive'belt and having a reach thereof passing beneath said roll and above said abrasive belt.

14. In a machine for finishing propeller blades, in combination, a frame having a generally hori- 'zontal bed, a blade support movable longitudinally on said bed, a head bracket carried by said frame above said bed and adjustable toward and from said bed, guide rollers carried by said frame on opposite sides of and remote from said roll, a pressure roll adjustably supported on said bracket, an abrasive belt having a reach passing between said roll and the blade on said support, a plurality of rollers disposed about said roll in generally parallel relation therewith, said second mentioned rollers being carried by said head bracket and adjustable therewith relative to said abrasive belt and said guide rollers therefor, and

, a cushioning belt supported on said second mentioned rollers having a reach thereof running parallel with the reach of-saidabrasive belt and between the latter and said roll.

'15; In a machine for finishing propeller blades, in combination, a frame having a generally horizontal bed, a carriage movable longitudinally on said bed having a blade supported thereon in a substantially horizontal position, a head bracket carried by said frame, a roll supporting'bracket carried by said head bracket and adjustable on the latter toward and from the blade on said support, a roll journalled in said bracket, means for oscillating said roll in timed relation to longitudinal movements of said carriage, an abrasive belt having a reach passing between said roll and the blade on said support, a plurality of rollers carried by said roll supporting bracket in generally parallel relation to said roll and spaced about the periphery of the latter, and a cushioning belt running over said rollers and having a reach thereof disposed'between said roll and the reach of said abrasive belt.

"16. Ina machine for finishing both the fiat and the camber sides of the propeller blades having pitch changes between the'hub and the tip portions thereof, in combination, a frame, a head, aplurality of guide rollers supported in generally parallel relation on said frame aboutsaid' head, a belt running over said rollers having an. outer abrasive surface, a blade supporting carriage disposed on one side of a generally horizontal reach of said belt, a pressure roll carried by said head on the other side of said belt for engaging the latter with a blade on said carriage, said roll having a groove cut in its surface extendingpart way about its periphery and having an uncut portion between the extremities of said groove, said groove corresponding in length to the length of the blade'to be finished and having a surface contour-corresponding to the contour of the camber side of the finished blade, means for reciprocating the carriage to reciprocate said blade beneath said roll, means for oscillating said roll aboutits axis in timed relation to said longitudinal movements to bring said grooved portion progressively over corresponding portions of the camber side of said blade, means for clamping said bladeto said carriage permitting rotation of the blade about its longitudinal axis to bring either the flat side or the camber side of the blade uppermost, and means for adjusting said pressure roll toward and from said blade to bring either the cut or the uncut peripheral portion of said roll into position to finish the side of saidblade which is uppermost.

1'7.' In a machine for finishing both the fiat and the camber sides of propeller blades having pitch changes between the hub and the tip portions thereof, in combination, a frame, a head, a plurality of guide rollers supported in generally parallel relation on said frame about'said head, a belt running over said rollers having an outer abrasive surface, a blade supporting carriage disposed on one side of a generally horizontal reach of said belt, a pressure roll carried by said head ll t on the otherside of said belt for engaglngithe latter with a blade on said carriage, said roll having a groove cut in its surface extending part way about its periphery and having an uncutportion between the extremities of" said groove; =said groove corresponding in length-to the length of the blade to be finished and'having a surface contour corresponding tothecontou-r of the camber side of the finished blade, means' for reciprocating the carriage to reciprocate" said' blade beneath of it periphery grooved to conform in contour progressively to changes in-contour oi-the camber V faceof the blade to be finished-fromhub-to tip of the latter, andmeansifor reversely oscillating said roll in timedfrelation to the longitudinal reciprocationsrof said carriage; v V 1 20. A generally cylindrical pressurelroll sior pressing a travelling :abrasivexbelt againstpa lonsaid roll, means for' oscillating said roll in timed blade to bring the periphery ofs'aid roll into pressure relationship with said blade; and means for releasing the connection betweerrsaid 'gear and said roll-permitting said roll'tobe driven by said belt when'the-uncut portion of-said roll is adjusted to bear against the fiat side of said blade.

' '18. 'In a blade finishing machine','in combination, a head, a plurality of guide rollers supported in generally parallel relation about said head, a belt running over said rollersy-means' fo-r driving said'belt at high linear speed, a'blade holder located beneath the lower reach' or said belt having means for 'elam-pinga blade thereon lengthwise or saidbelt, one of'said rollers comprising acontact-"roller supported on saidhead on the opposite'side of salid'beltfrom said blade and having an elongated peripheral "recess in the face thereo f cor'responding to the contour of the cam-"- her side or the blade,- d-rive meansr for eflectin'g reciprocatory movements of'said contact roll and bladerelative to each other -'longitudinally of said blade atlow linear speed relative to the speed of said belt, means for rockingsaid contact roll and blade; relative to each other'a'bout the gitudinally:reciprocating propellerlblade. to; finish the camber sidelthereofiasztheroll oscillates .in timed relation to said longitudinal movements, said roll including a right-cylindricalsuriacehaving 'a' circumferentialwgroove formed in a major portion of .said' surface; said groove being located intermediate the ends-ofzthe roll and-correspond;-

ing in contour, tothe, camber'side of-the propeller blade, the margins of said groove. including-both the sides-and ends thereof being bounded by continuous portions of saidrroll.surfacespa V 21; A='- generally i cylindrical -pressure;r0115v for pressing .1 a travelling ;.abr,asiv,,e belt =:ag ainst; a longitudinally; reciprocating propellers, blade :to

finish both the flat and etheacamber faces thereof; roll: driving zmeanszfor; oscillating said -rollin timed relation to; the longitudinal;reciprocating movements of said blade having a releasable connectionwithsaidmoll; :said roll including a right cylindricalsurface-having amaior-circumferential portion of it .cylindricalrsurface; grooved to pro vide a. surface ,impression-,- oi themambei facege-I a blade for pressing the: b elt;against; th camber face of: the blade, :as the 1011 yoscillates w timed relation to said longitudinal movem nts-an have ing-the remainder of itss cylindrical surfac M tween the ends of the groove ungrooved'fgr pres sr ing' the belt against :the fiat, iacej'of: the blade when said roll is-released.from said rlriving means.

longitudinal axis. of 7 saidblade to follow pitch 7 changes in said blade during such longitudinal movement, andmeans' for oscillating said contact roller" aboutdt's transverse aXi's by the relative longitudinal movements of said roller and blade and in timed relation to said longitudinal movements.

Y 19. 111 a bladefinishingmachina a 'frame including a bedg a carriage reciprocablealong said bed, means for effecting longitudinal reciprocation of said carriage; a blade holder-adapted to have a; blade secured thereto longitudinally of said carriagewith' either ia'ce uppermost -means for supporting said blade holder on "said carriage port, a pressure roll carriediby said frame 'in' position above the-reachrof said abrasive. belt to 7 engage the latter with the faceof said blade which 1s uppermost, said roll having a major portion 2- 2..--In: a a machine iorfinishing ;irregula1 ly shaped articles, 'incombination, a travelling belt having an abrasive surface-a work suppom a contact roll for positioning the abrasive surtace of said beltrelative-to aepiece o-fiworl; 013; said support, said roll. having a-peripheraldepressiqn therein constituting a developed i1npression, of

a' surface of a finished work piece,, means-for ei;- fecting relative. reciprocatory movements between saidrroll and saidworkpiece, 1means ionoscillate ingsaid roll about its axisdn timed relationrwith said lreciprocatory -movements; and -;means for effecting-relative adjustment of said roll and work support toward and ,from eachothera SIGMUND A. CZA RNEC KI. o EFEnilN QES Q T D 1" followingreferences areof record in file of thislpatent: .t 3,. r v UNITE sTATEs PA'IlEfNTS Ntmbe'r- 

